Carl Jung maintained until his death that the Liber Novus, the latter-day illuminated manuscript he moiled over for a decade and a half and then squirreled away from the public eye, possessed a radiance beyond his ken. It could only, he said, have been mined from the global subconscious. The same could be said about The Gathering, the Red Book-inspired new record that finds Baltimore psych long-shots Arbouretum reborn as sludge-folk conquerors. Not to slight the band’s previous work — the mossy meander of their first three LPs, especially 2007’s Rites of Uncovering, held some heady moments courtesy of headman Dave Heumann’s gordian knots of guitar — but it rings hollow next to the unfuckwithable lurch of this new set. Maybe it was the lineup substitution of synths-and-sticks man Matthew Pierce for former second-guitar Steve Strohmeier; maybe it was, in fact, that highfalutin Jungian inspiration.

Either way, from minute one these guys come off like they’re on the out end of an ayahuasca ritual, with a sequoia-thick sound full of lichen and leather. “The White Bird” revels in its lavish Master of Reality drone as Heumann’s meady baritone absolutely sells his versified fables of crumbling spires and truth in the wilderness. His calligraphic solos cut through the doom-y murk like a knife through marshwater, dexterously riding J.V. Brian Carey’s kick-heavy beat and never lapsing into decadent jam. It’s like Electric Folk with added amperage, a crossbreed of Bonnie “Prince” Billy’s undying ode to death I See A Darkness, Fairport Convention in “Matty Groves” mode, and a bit of Neurosis. Child ballads seem to peer out from behind the deep-fried American surface, betraying an ancientness that refuses to be bound by our 500-odd-year colonialized history.

Jimmy Webb’s “The Highwayman” forms the nucleus of the album, gracefully trussing together its thematic concerns and providing a respite from all the cymbal-crashing and slate-grey crunch. The song, inspired by a hotel-room dream, follows a man’s soul through four alternate selves: the titular man of the road, a weary sailor, a laborer constructing the Hoover Dam, and a trekking space-pilot. It delineates the story of America without resorting to broad signifiers, touching on reincarnation and the global subconscious without getting too cosmic on us. Neumann’s solemn reading avoids the schmaltz that spoils the version by the Nelson-Jennings-Kristofferson-Cash supergroup who took its name, as well as Webb’s own various overwrought recordings of it.

Arbouretum succeed through absolute concentration and craftsmanship, eschewing the easy crescendoes of mid-aughts post-rock in favor of more organically evolving swells. When they finally bust loose on the Iliadic final track “Song of the Nile,” every overdriven wailing peak has been thoroughly earned with slow-burning toil. The Gathering is devoid of gimmickry or subgenre convention, a diorite slab of lordly riffing inscribed with folkloric spirituality. Whatever they’ve tapped into here, whether it’s born of visionary experiences or just plain elbow grease, let’s pray they don’t lose track of it.